Jan 28 (AAP) THE US will bring a fresh resolution to the UN Human Rights Council in a bid to force Sri Lanka to deliver on promises to investigate its troops for war crimes, top US diplomats say after talks with Colombo.

"The US has decided to sponsor a procedural resolution (against Sri Lanka) at the March 2013 sessions of the UNHRC," Deputy Assistant Secretary of State James Moore said on Monday.

The US recognised Sri Lanka had made "some progress" since the previous US-led censure of Sri Lanka at the March 2012 UNHRC sessions in Geneva, but Washington believed more needed to be done, Moore said.

"The US and the other 23 members of the UNHRC who voted for that resolution in 2012 believe that the government of Sri Lanka needs to fulfil its commitments made to its own people," Moore said.

He said the fresh resolution to be moved in March was a reflection of "US commitment" to the people of Sri Lanka, which emerged from nearly 37 years of ethnic bloodshed in May 2009 after security forces crushed Tamil rebels.

The US has been highly critical of Sri Lanka's human rights record and has refused to train several of its senior military officers, saying they were linked to credible allegations of war crimes and crimes against humanity.

Another top US diplomat, Deputy Assistant Secretary of Defence Vikram Singh, said the US wanted to keep Sri Lanka's case fresh at Geneva by moving a new resolution against the Indian Ocean island.

He said the government's impeachment of the country's chief justice, despite two court rulings that the process was illegal and against the constitution, also contributed to the US decision for a fresh resolution.

"It is safe to say that the impeachment of the Chief Justice also contributed to the decision to ensure that the record (against Sri Lanka) stays fresh in Geneva," Singh told reporters in Colombo.
The US has asked Sri Lanka to reconsider the sacking of Shirani Bandaranayake following an international outcry over the impeachment earlier this month, in what activists have said was an assault on the independence of the judiciary.

Sri Lanka has been accused of killing up to 40,000 civilians in the final months of fighting separatist Tamil rebels who were known for their trade mark suicide bombings. Colombo has denied any civilians were killed by its troops.